Serena Williams has tennis players buzzing about a possible return after she playfully dodged questions about re-entering the sport's anti-doping testing pool during a television appearance that left more questions than answers.

Like other players from Ukraine, Svitolina does not shake hands with opponents from Russia or Moscow's ally Belarus because of the war.

Rybakina has made the Melbourne final once before, in 2023 when she lost in three tough sets to Aryna Sabalenka.

The 22-year-old Alcaraz is yet to drop a set as he arrows in on a maiden Australian Open crown.

Sabalenka, the top seed from Belarus, is aiming to win a third Melbourne crown in four years and looks in ominous form, yet to drop a set.

Australian Open organisers urged fans to drink plenty of water and stay in the shade as the tournament braces for a freak heatwave on Tuesday with temperatures set to soar as high as 45C.

Both players were distracted by an air show in the skies over Melbourne Park to mark Australia Day, and three double faults on Keys' opening serve gifted Pegula the advantage again in set two.

Learner Tien battled through a nosebleed to thrash three-time finalist Daniil Medvedev at the Australian Open on Sunday and make a Grand Slam quarter-final for the first time.

She will play another fast-rising teenager, American Iva Jovic, or Kazakhstan's Yulia Putintseva for a place in the semi-finals.

Extreme heat triggered a suspension of play on outside courts at the Australian Open on Saturday and briefly held up the match involving champion Jannik Sinner before his encounter resumed under a closed roof.

American 18-year-old Iva Jovic pulled off the biggest upset of her young career when she stunned Italian seventh seed Jasmine Paolini 6-2, 7-6(3) at the Australian Open on Friday for her first Grand Slam last-16 appearance.

Six-time Grand Slam winner Carlos Alcaraz was put through his paces by German journeyman Yannick Hanfmann on Wednesday before swatting him aside to book his place in the Australian Open third round.

The world number one saw off the awkward Bai 6-3, 6-1, having threatened at one stage to complete the job in even more express fashion.

The American ninth seed was a bundle of nerves on Rod Laver Arena, but calmed down to clinch a 7-6 (8/6), 6-1 win over Ukraine's Oleksandra Oliynykova.

Gauff started her quest for a maiden Australian Open title with a 6-2 6-3 win over Kamilla Rakhimova.

Aryna Sabalenka warned she was only going to get better as the top seed recovered from a slow start to launch her Australian Open with a straight-sets win on Sunday.

Play was halted during an Australian Open first-round match Sunday when a ball girl fainted as temperatures soared, with players Zeynep Sonmez and Ekaterina Alexandrova rushing to help her.

Alexander Zverev overcame a shaky start before reaching the second round on Sunday's first day of the Australian Open, as top-ranked Carlos Alcaraz and Aryna Sabalenka get set to enter the fray.

Former Wimbledon champion Marketa Vondrousova withdrew from the Australian Open on Sunday after the Czech player said she was dealing with a shoulder injury.

Alcaraz starts his bid for a career Grand Slam, with the Australian Open the only title missing from his collection.